Image processing apparatus and memory access method therefor

Abstract

An image processing apparatus and a memory access method use a memory control circuit to cyclically switch memory-access-job requests from a scanner, a printer, a facsimile machine, a page-description-language circuit, an interface circuit, and a refresh circuit whenever a storage medium in an image memory circuit is accessed.

What is claimed is:  
     
       1. An image processing apparatus capable of alternative modes of operation for controlling access requests from a plurality of devices for performing different data processes, said image processing apparatus comprising: 
       a memory; and  
       control means for cyclically switching memory access requests from said plurality of devices whenever said memory is accessed in one operation mode, wherein said control means permits consecutive access to a predetermined memory access request from one of said plurality of devices in another operation mode.  
     
     
       2. An image processing apparatus according to  claim 1 , wherein when one memory access request in succeeding order is not generated, said control means skips to execute the next memory access request. 
     
     
       3. An image processing apparatus according to  claim 1 , further comprising first setting means for assigning high or low priority to one predetermined memory access request from said plurality of devices, wherein said control means executes the predetermined memory access request in accordance with the high or low priority set by said first setting means. 
     
     
       4. An image processing apparatus according to  claim 3 , wherein when said memory is a refreshing storage device, said first setting means assigns the high priority to a refresh job request for said memory. 
     
     
       5. An image processing apparatus according to  claim 1 , further comprising second setting means for assigning a consecutive access right to one predetermined memory access request, wherein said control means executes the predetermined memory access request by performing consecutive access. 
     
     
       6. A memory access method for an image processing apparatus for controlling access requests from a plurality of image input and/or output apparatuses using a single memory to perform different data processes, said memory access method comprising the step of cyclically switching memory-access-job requests from said plurality of image input and/or output apparatuses whenever the memory is accessed. 
     
     
       7. A storage medium for storing a computer-readable program for an image processing apparatus controlling memory access requests from a plurality of devices using a single memory to perform different data processes, said computer-readable program comprising code for cyclically switching memory access requests from said plurality of devices whenever the memory is accessed, wherein consecutive access to a predetermined memory access request from one of said plurality of devices is permitted.